solar cell

Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas.
Image Credit: University of Chicago Illinois

Researchers at the University of Illinois at Chicago have found a new way to convert solar energy into usable energy. They have made a new solar cell that can efficiently convert atmospheric carbon dioxide into energy dense fuel instead of changing solar energy into electrical energy like conventional cells.

“The new solar cell is not photovoltaic – it’s photosynthetic. Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight,” says Amin Salehi-Khojin, assistant professor at UIC and author on this research.

The process by which energy is produced by these solar cells is a bit similar to photosynthesis in plants as both use carbon dioxide and water in the presence of light to form heavier compounds. However, products are different. Plants produce fuel in the form of sugar, especially glucose, but these solar cells produce syngas or synthesis gas. Syngas is a mixture of hydrogen gas and carbon monoxide. It can be burnt or changed into energy dense hydrocarbons like diesel, petroleum and other hydrocarbon fuels.

Researchers are using series of reduction reactions to convert carbon dioxide into hydrocarbon fuels than can be burnt easily to produce energy. This reaction can take place in the presence of the catalyst. However, the reduction reactions require precious metals like silver, which are inefficient. This makes reactions expensive and inefficient. Therefore, scientists were unable to use this method to change carbon dioxide into dense hydrocarbon fuels.

Now, researchers have found a family of nano-structured compounds called transition metal called dichalcogenides or TMDCs as the catalyst. Among them, nanoflake tungsten diselenide is the best catalyst.

However, the active site of TMDCs is easily oxidised and poisoned during the course of the reaction. So, researchers had to use ethyl methyl imidazolium tetrafluoroborate which was mixed with equal volume of water. The combination of water and liquid would make a co-catalyst that would preserve the catalyst active sites under the harsh condition.

“The new catalyst is more active; more able to break carbon dioxide’s chemicals bonds. In fact, it is 1,000 times faster than noble-metal catalysts and about 20 times cheaper.” Says UIC postdoctoral researcher and author of the paper Mohammad Asadi.

“The solar cells consists of two silicon triple-junction photovoltaic cells of 18 centimetres to harvest light; the tungsten diselenide and ionic liquid co-catalyst system on the cathode side; and cobalt oxide in potassium phosphate electrolyte on the anode side.”

When the light of 100 watts per square meter energises the cell, syngas is produced at cathode whereas free oxygen and hydrogen ions are produced at the anode.

“The hydrogen ions diffuse through a membrane to the cathode side to take part in carbon dioxide reduction reaction,” said Asadi.

If we could properly develop this technology properly and increase the efficiency of the cell, it could be helpful in different fields. Not only it could be helpful to produce energy in future, it would be helpful to prevent the extinction of fossil fuels and prevent climate change too. Besides this, it has possibility be used in small scale in future to produce energy.


This article is published by taking reference from Science Journal.





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New solar cells produces fuel in presence of CO2 and sunlight
Researchers at the University of Illinois at Chicago have made a new solar cell that converts atmospheric carbon dioxide into a high-energy hydrocarbon.
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